Fix bug in roughTopNames
Fix bug in roughTopNames

roughTopNames was returning a name that in fact might be
"looked though" by the rule matcher. Result: a rule
that should match was being pre-emptively discarded.

See Note [Care with roughTopName].

Fixes a bug noticed by Pedro (Trac #4918).

ezyang/ghc,sdiehl/ghc,ryantm/ghc,siddhanathan/ghc,gridaphobe/ghc,anton-dessiatov/ghc,TomMD/ghc,oldmanmike/ghc,GaloisInc/halvm-ghc,tjakway/ghcjvm,lukexi/ghc,snoyberg/ghc,holzensp/ghc,wxwxwwxxx/ghc,sdiehl/ghc,ghc-android/ghc,lukexi/ghc-7.8-arm64,hferreiro/replay,gcampax/ghc,ryantm/ghc,vikraman/ghc,tibbe/ghc,ghc-android/ghc,snoyberg/ghc,ml9951/ghc,tjakway/ghcjvm,tjakway/ghcjvm,shlevy/ghc,da-x/ghc,hferreiro/replay,oldmanmike/ghc,nathyong/microghc-ghc,forked-upstream-packages-for-ghcjs/ghc,olsner/ghc,sgillespie/ghc,forked-upstream-packages-for-ghcjs/ghc,TomMD/ghc,anton-dessiatov/ghc,spacekitteh/smcghc,ezyang/ghc,forked-upstream-packages-for-ghcjs/ghc,ryantm/ghc,oldmanmike/ghc,gcampax/ghc,elieux/ghc,jstolarek/ghc,hferreiro/replay,shlevy/ghc,mcschroeder/ghc,wxwxwwxxx/ghc,TomMD/ghc,fmthoma/ghc,bitemyapp/ghc,christiaanb/ghc,bitemyapp/ghc,tibbe/ghc,ezyang/ghc,ml9951/ghc,nomeata/ghc,mfine/ghc,siddhanathan/ghc,fmthoma/ghc,mettekou/ghc,gcampax/ghc,urbanslug/ghc,GaloisInc/halvm-ghc,spacekitteh/smcghc,urbanslug/ghc,elieux/ghc,siddhanathan/ghc,urbanslug/ghc,urbanslug/ghc,GaloisInc/halvm-ghc,nushio3/ghc,nkaretnikov/ghc,oldmanmike/ghc,holzensp/ghc,sgillespie/ghc,lukexi/ghc,bitemyapp/ghc,ekmett/ghc,siddhanathan/ghc,acowley/ghc,wxwxwwxxx/ghc,ml9951/ghc,gridaphobe/ghc,hferreiro/replay,sgillespie/ghc,gcampax/ghc,mettekou/ghc,gridaphobe/ghc,tibbe/ghc,green-haskell/ghc,ghc-android/ghc,gcampax/ghc,AlexanderPankiv/ghc,tjakway/ghcjvm,gridaphobe/ghc,frantisekfarka/ghc-dsi,ghc-android/ghc,frantisekfarka/ghc-dsi,gridaphobe/ghc,acowley/ghc,nkaretnikov/ghc,anton-dessiatov/ghc,nushio3/ghc,christiaanb/ghc,fmthoma/ghc,mcschroeder/ghc,acowley/ghc,elieux/ghc,TomMD/ghc,jstolarek/ghc,ilyasergey/GHC-XAppFix,nkaretnikov/ghc,elieux/ghc,fmthoma/ghc,vikraman/ghc,frantisekfarka/ghc-dsi,olsner/ghc,siddhanathan/ghc,mcmaniac/ghc,ryantm/ghc,green-haskell/ghc,ghc-android/ghc,GaloisInc/halvm-ghc,sgillespie/ghc,TomMD/ghc,forked-upstream-packages-for-ghcjs/ghc,nathyong/microghc-ghc,nkaretnikov/ghc,vTurbine/ghc,mfine/ghc,vikraman/ghc,mfine/ghc,tjakway/ghcjvm,gcampax/ghc,TomMD/ghc,nathyong/microghc-ghc,ml9951/ghc,green-haskell/ghc,elieux/ghc,ilyasergey/GHC-XAppFix,ilyasergey/GHC-XAppFix,forked-upstream-packages-for-ghcjs/ghc,nomeata/ghc,shlevy/ghc,mfine/ghc,vTurbine/ghc,olsner/ghc,hferreiro/replay,lukexi/ghc,vikraman/ghc,bitemyapp/ghc,forked-upstream-packages-for-ghcjs/ghc,anton-dessiatov/ghc,mettekou/ghc,mcmaniac/ghc,snoyberg/ghc,AlexanderPankiv/ghc,mcschroeder/ghc,mcmaniac/ghc,siddhanathan/ghc,ml9951/ghc,nushio3/ghc,fmthoma/ghc,vTurbine/ghc,hferreiro/replay,wxwxwwxxx/ghc,acowley/ghc,spacekitteh/smcghc,snoyberg/ghc,frantisekfarka/ghc-dsi,lukexi/ghc-7.8-arm64,ekmett/ghc,da-x/ghc,christiaanb/ghc,ekmett/ghc,gridaphobe/ghc,TomMD/ghc,ml9951/ghc,lukexi/ghc-7.8-arm64,nushio3/ghc,da-x/ghc,AlexanderPankiv/ghc,urbanslug/ghc,ml9951/ghc,nkaretnikov/ghc,mcschroeder/ghc,christiaanb/ghc,mcmaniac/ghc,da-x/ghc,elieux/ghc,da-x/ghc,shlevy/ghc,mcmaniac/ghc,AlexanderPankiv/ghc,christiaanb/ghc,sgillespie/ghc,forked-upstream-packages-for-ghcjs/ghc,vTurbine/ghc,sdiehl/ghc,mfine/ghc,olsner/ghc,ezyang/ghc,nushio3/ghc,tjakway/ghcjvm,vikraman/ghc,holzensp/ghc,AlexanderPankiv/ghc,mfine/ghc,lukexi/ghc-7.8-arm64,gridaphobe/ghc,lukexi/ghc,sdiehl/ghc,tibbe/ghc,mcschroeder/ghc,christiaanb/ghc,oldmanmike/ghc,elieux/ghc,olsner/ghc,wxwxwwxxx/ghc,ekmett/ghc,shlevy/ghc,anton-dessiatov/ghc,vikraman/ghc,fmthoma/ghc,mcschroeder/ghc,acowley/ghc,ghc-android/ghc,ryantm/ghc,AlexanderPankiv/ghc,nathyong/microghc-ghc,mettekou/ghc,ilyasergey/GHC-XAppFix,AlexanderPankiv/ghc,nomeata/ghc,sdiehl/ghc,mettekou/ghc,lukexi/ghc-7.8-arm64,ml9951/ghc,jstolarek/ghc,holzensp/ghc,wxwxwwxxx/ghc,fmthoma/ghc,spacekitteh/smcghc,vTurbine/ghc,acowley/ghc,mettekou/ghc,shlevy/ghc,nkaretnikov/ghc,sgillespie/ghc,nushio3/ghc,urbanslug/ghc,sdiehl/ghc,nkaretnikov/ghc,wxwxwwxxx/ghc,ekmett/ghc,green-haskell/ghc,vTurbine/ghc,olsner/ghc,da-x/ghc,nathyong/microghc-ghc,frantisekfarka/ghc-dsi,vikraman/ghc,jstolarek/ghc,jstolarek/ghc,vTurbine/ghc,snoyberg/ghc,christiaanb/ghc,lukexi/ghc,olsner/ghc,bitemyapp/ghc,ezyang/ghc,tjakway/ghcjvm,GaloisInc/halvm-ghc,ghc-android/ghc,da-x/ghc,snoyberg/ghc,mcschroeder/ghc,nushio3/ghc,nomeata/ghc,anton-dessiatov/ghc,ezyang/ghc,sgillespie/ghc,GaloisInc/halvm-ghc,gcampax/ghc,oldmanmike/ghc,tibbe/ghc,spacekitteh/smcghc,holzensp/ghc,mfine/ghc,green-haskell/ghc,mettekou/ghc,oldmanmike/ghc,urbanslug/ghc,siddhanathan/ghc,nathyong/microghc-ghc,acowley/ghc,sdiehl/ghc,nathyong/microghc-ghc,GaloisInc/halvm-ghc,nomeata/ghc,shlevy/ghc,hferreiro/replay,snoyberg/ghc,ezyang/ghc,anton-dessiatov/ghc